ACAT-1, Cav-1 and PrP expression in scrapie susceptible and resistant sheep

Abstract

Scrapie is a prion disease for which no means of ante-mortem diagnosis is available. We recently found a relationship between cell susceptibility to scrapie and altered cholesterol homeostasis. In brains and in skin fibroblasts and peripheral blood mononuclear cells from healthy and scrapie-affected sheep carrying a scrapie-susceptible genotype, the levels of cholesterol esters were consistently higher than in tissues and cultures derived from animals with a scrapie-resistant genotype. Here we show that intracellular accumulation of cholesterol esters (CE) in fibroblasts derived from scrapie-susceptible sheep was accompanied by parallel alterations in the expression level of acyl-coenzymeA: cholesterol-acyltransferase (ACAT1) and caveolin-1 (Cav-1) that are involved in the pathways leading to intracellular cholesterol esterification and trafficking. Comparative analysis of cellular prion protein (PrPc) mRNA, showed an higher expression level in cells from animals carrying a susceptible genotype, with or without Scrapie. These data suggest that CE accumulation in peripheral cells, together with the altered expression of some proteins implicated in intracellular cholesterol homeostasis, might serve to identify a distinctive lipid metabolic profile associated with increased susceptibility to develop prion disease following infection.

In vitro synergistic anti-prion effect of cholesterol ester modulators in combination with chlorpromazine and quinacrine

“…These results confirm and extend our previous findings in the same cell model [14] and in the ovine scrapie [11][12][13], and further support the presence of a tight association between prion infection/susceptibility and altered cholesterol homeostasis. In agreement with our results, altered cholesterol metabolism/esterification with over-expression of ACAT-1 (soat1) was reported in mice brains during the course of experimental scrapie [34, refs therein], and up-regulation of cholesterol biosynthesis was recently described following prion A total of 30x10 6 of each cell culture was collected from sub-confluent flasks.…”

“…Interestingly, Bach et al [35] presented evidence that modification of cholesterol biosynthesis appears a characteristic response of neurons and neuronal cell lines to prion challenge, and suggested that prions themselves may have the potential to alter cell cholesterol homeostasis in a cell-type specific manner. Although at present we have no mechanistic explanation for the association found in sheep between cholesterol alteration and scrapie-susceptible prion genotype [11][12][13], we can speculate that prions may as well have the potential to alter cholesterol homeostasis in a genotypetype specific manner. Whatever mechanism is involved, the emerging picture is that of a direct relationship between prion infection/replication and lipid homeostasis alterations.…”

“…Thus, efforts should be made to identify more successful therapeutic approaches, as well as novel molecular targets of prion generation. In this context, our studies on the role of cholesterol in cell susceptibility to prion infection/replication showed that brains and ex vivo dermal fibroblasts and peripheral blood mononuclear cells (PBMCs) from sheep genetically susceptible-to or suffering-from scrapie, displayed higher cholesterol ester (CE) levels than sheep carrying a scrapie-resistant genotype, and altered expression levels of the acyl-coenzymeA:cholesterolacyltransferase (ACAT-1; up-regulated) and caveolin-1 (Cav-1; down-regulated) involved in cholesterol esterification and trafficking, respectively [11][12][13]. In addition, in persistently prion-infected N2a cells, we found that drugs able to reduce the CE pool, i.e.…”

Cholesterol homeostasis: a key to prevent or slow down neurodegeneration

“…A significant amount of genetic, biochemical, and pharmacological data highlighted that modifications in cholesterol esterification and trafficking are associated with Aβ and PrPsc biogenesis (Puglielli et al, 2001; Hutter-Paier et al, 2004; Bhattacharyya and Kovacs, 2010; Huttunen et al, 2010; Pani et al, 2007a,b,c, 2011; Orrù et al, 2010a,b,c). Moreover, several studies in various cell and animal models of AD evidenced that, genetic or pharmacological inhibition of ACAT activity markedly suppresses Aβ generation.…”

Pharmacologic Cholesterol Homeostasis Affects Prion Generation in a Synergistic Manner

“…The overall complexity of the mechanism(s) linking PrP metabolism to cellular cholesterol changes is even more complicated by the fact that prion infection/replication itself seems to have the potential to induce modifications in the cholesterol metabolism [10,11]. In this context, our recent findings in sheep scrapie indicated that modifications of cholesterol metabolism, rather than being limited to the brain, appear to be a systemic trait since also ex vivo dermal fibroblasts and blood lymphocytes of sheep suffering-from or susceptible-to scrapie display similar alterations [12][13][14]. In addition, in prion/cell systems we found that persistent infection is associated to metabolic changes involving, besides cholesterol, all major classes of intracellular lipids, and that treatments with drug combinations triggering lipid homeostasis determine a synergic inhibition of prion generation [13,15,16].…”